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lib/vsprintf: Replace space with '_' before crng is ready 

Before crng is ready, output of "%p" composes of "(ptrval)" and
left padding spaces for alignment as no random address can be
generated. This seems a little strange when default string width
is larger than strlen("(ptrval)").

For example, when irq domain names are built with "%p", the nodes
under /sys/kernel/debug/irq/domains like this on AArch64 system,

[root@y irq]# ls domains/
default                   irqchip@        (ptrval)-2
irqchip@        (ptrval)-4  \_SB_.TCS0.QIC1  \_SB_.TCS0.QIC3
irqchip@        (ptrval)  irqchip@        (ptrval)-3
\_SB_.TCS0.QIC0             \_SB_.TCS0.QIC2

The name "irqchip@        (ptrval)-2" is not so readable in console
output.

This patch replaces space with readable "_" when output needs padding.
Following is the output after applying the patch,

[root@y domains]# ls
default                   irqchip@(____ptrval____)-2
irqchip@(____ptrval____)-4  \_SB_.TCS0.QIC1  \_SB_.TCS0.QIC3
irqchip@(____ptrval____)  irqchip@(____ptrval____)-3  \_SB_.TCS0.QIC0
\_SB_.TCS0.QIC2

There is same problem in some subsystem's dmesg output. Moreover,
someone may call "%p" in a similar case. In addition, the timing of
crng initialization done may vary on different system. So, the change
is made in vsprintf.c.

Suggested-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Link: http://lkml.kernel.org/r/20180216210711.79901-7-andriy.shevchenko@linux.intel.com
To: "Tobin C . Harding" <me@tobin.cc>
To: linux@rasmusvillemoes.dk
To: Joe Perches <joe@perches.com>
To: linux-kernel@vger.kernel.org
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Joey Zheng <yu.zheng@hxt-semitech.com>
Signed-off-by: Shunyong Yang <shunyong.yang@hxt-semitech.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
hifive-unleashed-5.1
Shunyong Yang 2018-02-16 23:07:09 +02:00 committed by Petr Mladek
parent 496a9a5f38
commit 91efafb1dd
1 changed files with 2 additions and 1 deletions
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3
lib/vsprintf.c
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@ -1681,12 +1681,13 @@ early_initcall(initialize_ptr_random);
/* Maps a pointer to a 32 bit unique identifier. */
static char *ptr_to_id(char *buf, char *end, void *ptr, struct printf_spec spec)
{
const char *str = sizeof(ptr) == 8 ? "(____ptrval____)" : "(ptrval)";
unsigned long hashval;
if (unlikely(!have_filled_random_ptr_key)) {
spec.field_width = 2 * sizeof(ptr);
/* string length must be less than default_width */
return string(buf, end, "(ptrval)", spec);
return string(buf, end, str, spec);
}
#ifdef CONFIG_64BIT